In UMTS (Universal Mobile Telecommunications System) network, Long Term Evolution (LTE) is specified for the purpose of further high data rate and low delay, etc. (Non-Patent Document 1). In addition, for the purpose of further broadening and speeding up from the LTE, the successor system of LTE (for example, LTE-A (LTE-Advanced), FRA (Future Radio Access), 5G (5th generation mobile communication system), and New-RAT (Radio Access Technology), etc.) are also being studied.
In the radio communication system after LTE Rel. 13 (5G, for example), in order to make use of the given frequency spectrum more flexibly and effectively, introduction of a flexible duplex system that enables each subframe to be dynamically available as DL or UL has been studied. Flexible duplex does not prescribe DL/UL in advance for time/frequency resources, but dynamically changes DL/UL according to various conditions such as traffic and channel conditions.